1. Field of the Invention
The present invention relates to pivotally adjustable seatback arrangements, particularly for use in vehicles. More specifically, the present invention discloses an alternating and mating tooth and recess relationship, established between a cam-operated pawl pivotally secured to a seatback arm and an arcuate extending edge of a seat frame sector. The pawl is actuated by the cam to be interengageable with first and second arcuately offset locations along the seat frame sector, corresponding with upright and forwardly pivoted locations of the seatback arm relative to the seat frame.
2. Description of the Prior Art
The prior art is well documented with examples of seatback adjustment assemblies. U.S. Pat. No. 4,147,386, issued to Stolper, teaches a motor vehicle seat having a pivotal hinge fitting with a fixed component connected to a seat portion, a pivotal component connected to a backrest, a pivot pin connecting the fixed component to the pivoted component, and a toothed part rotatably mounted on the pivot pin. Fine-adjustment means on the pivotable component are operable to pivot the pivotable component to adjust the angle of the backrest relative to the seat portion.
The pivotal hinge fitting also includes means on the fixed component to limit turning of the toothed part in a direction corresponding to movement of the backrest away from the seat portion. Of note, an inertia pawl is mounted on the fixed component and engageable with the toothed part to prevent the movement of the backrest towards the seat portion.
U.S. Pat. No. 4,457,557, issued to Une, teaches a reclining device for use in a vehicle seat in which an intermediate bracket is rotatably supported on an eccentric shaft between a stationary bracket secured to a vehicle seat cushion and a movable bracket secured to a seatback. The stationary bracket and intermediate bracket are operatively connected together by a stepwisely adjustable engaging mechanism operable by an operation lever. A differential reduction gearing mechanism includes internal and external gears having the same pitch and differing in tooth number are interposed between the intermediate bracket and the movable bracket and a spiral spring acts between the stationary bracket and the intermediate bracket to urge the movable bracket so that the seatback is urged upwardly forwardly.
Sugimoto, U.S. Pat. No. 6,659,558, teaches a seat reclining device having a base plate secured to a seat cushion, an arm member secured to a seatback, upper and lower tooth plates pivotally mounted on a base plate and provided with upper and lower teeth, a cam member pivotally mounted on the base plate, and at least one support for the lower tooth plate. When the cam member moves the lower tooth plate in a direction to bring the lower teeth into contact with the upper teeth, the upper tooth plate is locked together with the arm member so that the seatback becomes unable to pivot relative to the seat cushion. In a locked position, the support supports the end portion of the lower tooth plate so as to maintain the engagement of the upper and lower teeth. Thus, the seat reclining device can lock the seatback with improved strength.
Moyer, U.S. Pat. No. 4,875,735, teaches a hinge fitting for a reclining seat structure which includes a fixed support bracket, a seatback member, a locking member and a lock actuating mechanism. The lock actuating mechanism includes a cam with two cam arms which move the locking member into locking and unlocking position. The shape and positioning of the cam result in a hinge fitting that is resistant to unlocking in response to a force applied to the seatback. The operator for the lock actuating mechanism is mounted remotely from the intersection of the seat and seatback.
Finally, U.S. Pat. No. 5,718,481, issued to Robinson, for a seat recliner mechanism. A single release handle adjusts the reclination angle of the seatback as well as dumping the seatback in a forwardly folded position. The recliner mechanism enables the reclining and forward folding motion to operate about a common axis or independent axes. The recliner mechanism is capable of latching the seatback in the forward folded position, thus making the mechanism convenient for use with removable seats. The same release handle may also be used to release the seatback from the forwardly folded position.